2.  Try naming the mapped fields exactly how they are on the attached screenshot and then importing.

Example:

Instead of <Item Description> try <ItemDescription>   (no space)

Instead of <Quantity> try <Qty>

Instead of <Total Value> try <AmountDue>     (no space)

Please let me know how this works for you.  If you're still having trouble, send me a private message on here and I will give you my email and you can send me the template and I'd be happy to take a look at it if you want.